BIAS-VOLTAGE-DEPENDENT AND BIAS-LIGHT-DEPENDENT HIGH PHOTOCURRENT GAINS IN AMORPHOUS-SILICON SCHOTTKY BARRIERS

Experimental results of very large, long-wavelength photocurrent gains in amorphous silicon-based Schottky barrier structures are reported. It is shown that these occur for devices in the space-charge current regime operated at forward bias voltages past the flatband condition. The analysis of microelectronic and photonic structures computer program is used to show that these high gains are due to hole trapping and the resulting modulation of the virtual cathode barrier potential at the ohmic contact. As demonstrated, these gains are bias voltage, bias light, monochromatic light intensity, material property, and device thickness dependent. This type of photocurrent gain is another photogating effect and is much different than the usual bulk photoconductive gain.